xSidebar - Brings the look and feel of Firefox style sidebars to clients Seamonkey. In addition, xSidebar also implements the infrastructure (the XUL clients elements and javascript APIs from Firefox) to make porting Firefox clients sidebar extensions to Seamonkey as painless as possible.

ChatZilla - An IRC chat client built using the Mozilla seamonkey framework.

ReloadEvery - Automatically reloads a web page every so many clients seconds or clients minutes.